A bromine redox-mediated electrochemical carbon dioxide capture and release system

Abstract

The present application relates to carbon dioxide capture and utilization technology field, disclose a kind of bromine oxygen reduction-mediated electrochemical carbon dioxide capture and release system, including electrochemical reaction module, anode liquid circulation module and cathode liquid circulation module.Cathode chamber occurs hydrogen evolution reaction, bicarbonate ion in cathode electrolyte migrates to anode chamber through anion exchange membrane and reacts with hydrogen ion generated by bromine oxidation reaction to release carbon dioxide;Anode electrolyte is regenerated by circulation through carbon dioxide release pool and anode liquid regeneration pool, and oxygen is generated in the process of thermal catalysis;Cathode electrolyte is regenerated by hydrogen separation and carbon dioxide absorption.The present application can realize the spatial separation of carbon dioxide and oxygen, reduce the working voltage of electrolytic cell, and realize the recycling of cathode and anode electrolyte.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture and utilization technology, and in particular to a bromine oxidation-reduction mediated electrochemical carbon dioxide capture and release system. Background Technology

[0002] Global energy-related CO2 emissions continue to grow, with atmospheric CO2 concentrations significantly higher than pre-industrial levels, further exacerbating the greenhouse effect. In industries such as steel, cement, and chemicals, where deep decarbonization is difficult to achieve, CO2 capture is typically necessary to reduce carbon emissions. The economic feasibility of carbon capture, utilization, and storage (CCUS) largely depends on the efficiency and cost of the CO2 capture process; reducing CO2 capture costs will promote the development of downstream utilization and storage technologies.

[0003] In recent years, electrochemical CO2 capture technology has developed rapidly. Among them, the hydrogen evolution reaction (HER) can be used as the cathode reaction driving electrochemical CO2 capture. During the HER process, a water reduction reaction occurs on the cathode side, causing a local pH increase on the electrode surface, which allows CO2 to be captured by the electrochemically generated OH-. - Absorbs and forms bicarbonate ions (HCO3-) - The bicarbonate ions migrate towards the anode under the influence of an electric field and react with hydrogen ions generated during the oxygen evolution reaction (OER), thereby releasing CO2 gas again.

[0004] However, in electrochemical CO2 capture systems employing anodic OERs, both CO2 release and O2 generation occur on the anode side. This leads to the CO2 released from the electrochemical reaction easily mixing with the anode product O2, typically requiring additional gas separation and purification steps, thus increasing system complexity and operating costs. Furthermore, the anode catalytic electrodes compatible with OERs are usually made of precious metals such as iridium and ruthenium, resulting in high costs and further limiting the large-scale application of electrochemical CO2 capture technology. In addition, OERs themselves have a significant kinetic barrier, requiring higher operating voltages for the electrolysis process, which also increases system energy consumption. Therefore, existing electrochemical CO2 capture and release systems still have room for improvement in terms of CO2 and O2 separation, anode catalytic electrode costs, and electrolysis energy consumption. Summary of the Invention

[0005] This invention aims to solve the problems of carbon dioxide and oxygen mixing, high cost of anode catalytic electrodes, and high cell voltage in existing electrochemical carbon dioxide capture and release systems, and proposes a bromine oxidation-reduction mediated electrochemical carbon dioxide capture and release system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A bromine redox-mediated electrochemical carbon dioxide capture and release system includes an electrochemical reaction module, an anolyte circulation module, and a cathode liquid circulation module;

[0008] The electrochemical reaction module includes a cathode chamber, an anode chamber, cathode catalytic electrodes and anode catalytic electrodes respectively disposed in the cathode chamber and anode chamber, and an anion exchange membrane separating the cathode chamber and anode chamber. In the cathode chamber, the cathode electrolyte undergoes a hydrogen evolution reaction to generate hydrogen gas and hydroxide ions; in the anode chamber, bromide ions in the anolyte first undergo an oxidation reaction to generate elemental bromine, which is further converted into bromate ions, bromide ions, and hydrogen ions; bicarbonate ions in the cathode electrolyte migrate to the anode chamber under the influence of an electric field via the anion exchange membrane and react with the hydrogen ions to generate carbon dioxide. Thus, the anolyte bromine oxidation reaction replaces the traditional anolyte oxygen evolution reaction, separating the carbon dioxide release process from the oxygen evolution process.

[0009] The anolyte circulation module includes a carbon dioxide release tank and an anolyte regeneration tank. The carbon dioxide release tank receives the anolyte flowing from the anode chamber and separates the carbon dioxide from it. The anolyte regeneration tank thermally catalyzes the anolyte treated by the carbon dioxide release tank, converting bromate ions in the anolyte into bromide ions and generating oxygen. The regenerated anolyte is then returned to the anode chamber as the anolyte for subsequent electrochemical reactions. By placing the carbon dioxide release process in the carbon dioxide release tank and the oxygen generation process in the anolyte regeneration tank, spatial decoupling of carbon dioxide release and oxygen generation on the anode side is achieved, preventing carbon dioxide and oxygen from mixing during the anode reaction.

[0010] The high-purity carbon dioxide described in this invention refers to a carbon dioxide release process in which the anodic reaction itself does not produce any side reactions that generate other gases, and the carbon dioxide release process and the oxygen generation process are spatially separated, thereby avoiding the mixing of oxygen generated by the anodic reaction with carbon dioxide; the release of the collected carbon dioxide can be characterized by the carbon dioxide release Faraday efficiency.

[0011] The catholyte circulation module includes a hydrogen separation tank and a carbon dioxide absorption tank. The hydrogen separation tank receives the catholyte flowing from the cathode chamber and separates the hydrogen from it. The carbon dioxide absorption tank allows the catholyte, after being treated by the hydrogen separation tank, to absorb carbon dioxide from the carbon dioxide-containing gas mixture, thereby regenerating the catholyte. The regenerated catholyte is returned to the cathode chamber for subsequent electrochemical reactions. Through the cooperation of the anolyte and catholyte circulation modules, the anolyte and catholyte can be cyclically regenerated during the electrochemical reaction, reducing the need for continuous electrolyte replenishment and enabling continuous operation of the system.

[0012] Specifically, in the anode chamber, bromide ions are converted into bromate ions and hydrogen ions through a bromine oxidation reaction. The hydrogen ions react with bicarbonate ions that migrate from the cathode chamber to the anode chamber via an anion exchange membrane to produce carbon dioxide and water. Simultaneously, a hydrogen evolution reaction occurs in the cathode chamber to produce hydrogen gas and hydroxide ions. The anolyte after the reaction in the anode chamber enters a carbon dioxide release tank for carbon dioxide separation, and then enters an anolyte regeneration tank, where bromate ions are thermally catalytically converted into bromide ions to produce oxygen, thus regenerating the anolyte. The catholyte after the reaction in the cathode chamber enters a hydrogen separation tank for hydrogen separation, and then enters a carbon dioxide absorption tank to absorb carbon dioxide from the mixed gas, thus regenerating the catholyte. This forms a reaction system in which the catholyte and anolyte each circulate independently.

[0013] Compared to electrochemical carbon dioxide capture systems that employ the anodic oxygen evolution reaction (OER), this invention uses a bromine oxidation reaction instead. Traditional anodic OER has a significant kinetic barrier, while the bromine oxidation reaction has a lower thermodynamic equilibrium potential, thus reducing the overall cell pressure during the electrochemical reaction. Simultaneously, by transferring the OER process to the anolyte regeneration tank, the oxygen generation process is spatially separated from the carbon dioxide release process, thereby preventing the mixing of carbon dioxide and oxygen. Furthermore, hydrophilicated graphite felt can be used as the anodic catalytic electrode on the anode side, replacing the noble metal catalytic electrode used in traditional OER reactions.

[0014] In some embodiments, the electrochemical reaction module adopts a sandwich structure, with the cathode chamber and the anode chamber separated by anion exchange membrane to form the cathode reaction region and the anode reaction region, respectively; the anion exchange membrane enables the migration of bicarbonate ions in the cathode electrolyte to the anode chamber, and, in conjunction with the hydrogen ions formed by the bromine oxidation reaction at the anode, completes the release of carbon dioxide.

[0015] In some embodiments, the carbon dioxide release tank releases carbon dioxide from the anolyte by nitrogen purging; the anolyte regeneration tank regenerates the anolyte and generates oxygen through thermal catalysis; the hydrogen separation tank separates hydrogen from the cathode electrolyte by nitrogen purging; and the carbon dioxide absorption tank regenerates the cathode electrolyte by absorbing carbon dioxide from a carbon dioxide-containing mixture. Thus, the system can simultaneously capture and release carbon dioxide while obtaining hydrogen, oxygen, and carbon dioxide, and achieve spatial separation of carbon dioxide and oxygen.

[0016] Preferably, the electrochemical reaction module is provided with a cathode guide plate, a cathode limit gasket, a cathode catalytic electrode, an anion exchange membrane, an anode catalytic electrode, an anode limit gasket, and an anode guide plate in sequence from the cathode side to the anode side, and a conductive plate is provided on the outer side of the anode guide plate.

[0017] Furthermore, the cathode catalytic electrode is a platinum-ruthenium carbon electrode supported on a nickel foam substrate.

[0018] Furthermore, the anode catalytic electrode is a hydrophilically treated graphite felt.

[0019] Furthermore, the anion exchange membrane is a polyimide anion exchange membrane.

[0020] Furthermore, the electrochemical reaction module uses a pure titanium plate as the cathode guide plate and a graphite plate as the anode guide plate, with a reaction area of ​​4 cm². 2 Current density 50~300 mA / cm 2 .

[0021] Furthermore, the electrochemical reaction module is a stack consisting of an outer pure titanium end plate and six stacked graphite electrode plates on the inner side, with a total reaction area of ​​600 cm². 2 The operating current density is 50~500 mA / cm². 2 .

[0022] Furthermore, the anolyte is a potassium bromide electrolyte solution, and the cathode electrolyte is a potassium bicarbonate electrolyte solution; the concentrations of both the potassium bromide electrolyte solution and the potassium bicarbonate electrolyte solution are 1 mol / L.

[0023] Furthermore, the anode guide plate is provided with an anode plate flow channel, which is one of an interdigitated flow channel, a serpentine flow channel, or a parallel flow channel.

[0024] Furthermore, the anode plate flow channel is an interdigitated flow channel, which is composed of multiple sets of interlocking and interlocking finger-shaped flow channel units. The lower port of the anode plate flow channel is the anode electrolyte inlet, and the upper port is the anode electrolyte outlet.

[0025] Furthermore, the anolyte regeneration tank is equipped with a ruthenium oxide catalyst and a stirring and heating device, wherein the stirring and heating device has a stirring rate of 200~1000 rpm and a heating temperature of 50~80℃.

[0026] Furthermore, the carbon dioxide release tank uses nitrogen purging to separate carbon dioxide from the anolyte, and the hydrogen separation tank uses nitrogen purging to separate hydrogen from the cathode electrolyte.

[0027] Furthermore, the carbon dioxide absorption cell is used to allow the cathode electrolyte to absorb carbon dioxide from the carbon dioxide-containing mixture.

[0028] Furthermore, both the cathode liquid circulation module and the anolyte circulation module are equipped with a conveying device for driving the electrolyte circulation flow.

[0029] Furthermore, the cathode electrolyte circulation module includes a peristaltic pump one and a peristaltic pump two. The peristaltic pump one is used to transport the cathode electrolyte in the hydrogen separation tank to the carbon dioxide absorption tank, and the peristaltic pump two is used to transport the cathode electrolyte in the carbon dioxide absorption tank to the cathode chamber. Preferably, the flow rate of both the peristaltic pump one and the peristaltic pump two is 100 mL / min.

[0030] Furthermore, the anolyte circulation module includes a peristaltic pump three and a peristaltic pump four. The peristaltic pump three is used to transport the anolyte in the anolyte regeneration tank to the anode chamber, and the peristaltic pump four is used to transport the anolyte in the carbon dioxide release tank to the anolyte regeneration tank. Preferably, the flow rate of both the peristaltic pump three and the peristaltic pump four is 20 mL / min.

[0031] The beneficial effects of this invention are as follows:

[0032] 1. This invention constructs a bromine redox-mediated electrochemical carbon dioxide capture and release system. Through the synergistic action of the electrochemical reaction module, anolyte circulation module, and catholyte circulation module, hydrogen generation, oxygen generation, and high-purity carbon dioxide release can be achieved simultaneously. It is applicable to the separation and capture of carbon dioxide in simulated industrial flue gas mixtures containing 80% N2, 15% CO2, and 5% O2. By using BrOR-mediated extraction, the carbon dioxide release process is spatially decoupled from the oxygen generation process, allowing oxygen to be generated independently in the anolyte regeneration tank. This avoids the problem of carbon dioxide and oxygen mixing in traditional electrochemical carbon dioxide capture processes, reducing the need for subsequent gas separation and purification. Simultaneously, relying on the anolyte and catholyte circulation modules, the anolyte and catholyte can be cyclically regenerated during the reaction process, reducing the need for continuous electrolyte replenishment and facilitating continuous system operation.

[0033] 2. This invention uses potassium bromide electrolyte solution as the anolyte, replacing the traditional OER with BrOR. Compared to the OER process, which requires the formation of O-O bonds and has a large kinetic barrier, BrOR does not require the formation of strong chemical bonds, thus offering better kinetic advantages. Simultaneously, the thermodynamic equilibrium potential of BrOR is lower than that of OER, thereby reducing the overall cell voltage during the electrochemical reaction and improving energy utilization efficiency. At 10 mA / cm²... 2 At the same current density, the electrolytic cell voltage of this invention is reduced by approximately 400 mV compared to the anodic OER. Furthermore, the use of hydrophilically treated graphite felt as the anodic catalytic electrode can replace the noble metal catalytic electrode relied upon in the traditional oxygen evolution reaction, thereby reducing the cost of using the anodic catalytic electrode.

[0034] 3. The anode plate flow channel of the present invention can adopt an interdigitated flow channel, a serpentine flow channel, or a parallel flow channel, wherein the interdigitated flow channel can improve the mass transfer of reactants and carbon dioxide release performance on the anode side. Compared with the serpentine flow channel and the parallel flow channel, at 100 mA / cm 2 BrO3 in interdigitated flow channels at current density - The Faraday efficiency reaches 99.7%, the cell voltage is 1.915 V, and the CO2 release Faraday efficiency reaches 96.3%. Its cell voltage is lower than that of serpentine and parallel flow channels, while its CO2 release Faraday efficiency is higher. (50~300 mA / cm²) 2 Within the current density range, the BrO3 in the system - The Faraday efficiency is no less than 97.67%, and the carbon dioxide release Faraday efficiency is no less than 89.38%, which can maintain high bromine oxidation reaction efficiency and carbon dioxide release efficiency.

[0035] 4. This invention exhibits good long-term operational stability. At 100 mA / cm²... 2 During a 500-hour continuous stability test at the current density, the cell voltage of the electrolytic cell increased by only about 195 mV, and the carbon dioxide release Faraday efficiency remained above 90%. At the same time, the pH of the cathode electrolyte and the anolyte did not change significantly, indicating that the system can maintain stable carbon dioxide release performance and electrochemical performance during long-term continuous operation.

[0036] 5. This invention has the capability for further scale-up operation. When using a 6×100 cm... 2 Under scale-up conditions for the reactor stack, the system can achieve 450 mA / cm². 2 Achieving kilowatt-level power operation at current density while maintaining a carbon dioxide release Faraday efficiency of 76.83% indicates that the electrochemical carbon dioxide capture and release system of this invention can still maintain carbon dioxide release performance under scale-up operating conditions, and has potential for industrial application. Attached Figure Description

[0037] Figure 1 This is a schematic diagram illustrating the main reactions in the cathode and anode chambers in Example 1 and the main reaction principle in the anolyte regeneration tank in Example 5 of the present invention.

[0038] Figure 2 This is a schematic diagram of the electrochemical reaction module in Embodiment 1 of the present invention. In the figure, 3 is the cathode catalytic electrode, 4 is the anode catalytic electrode, 5 is the anion exchange membrane, 14 is the cathode guide plate, 15 is the cathode limit spacer, 19 is the anode limit spacer, 20 is the anode guide plate, and 21 is the conductive plate.

[0039] Figure 3This is a schematic diagram of the structure of the bromine oxidation-reduction mediated electrochemical carbon dioxide capture and release system in Example 5 of the present invention. In the figure, 1 is the cathode chamber, 2 is the anode chamber, 3 is the cathode catalytic electrode, 4 is the anode catalytic electrode, 5 is the anion exchange membrane, 6 is the hydrogen separation tank, 7 is the carbon dioxide absorption tank, 8 is the carbon dioxide release tank, 9 is the anolyte regeneration tank, 10 is the peristaltic pump one, 11 is the peristaltic pump two, 12 is the peristaltic pump three, and 13 is the peristaltic pump four.

[0040] Figure 4 This is a comparison graph showing the change of current density in the electrolytic cell with voltage in Embodiment 1 and Comparative Example 1 of the present invention;

[0041] Figure 5 This is a diagram verifying the catalytic effect of ruthenium oxide in Example 2 of the present invention;

[0042] Figure 6 This is a comparison chart of the current density versus the tank voltage for different anode plate flow channels in Embodiment 4 of the present invention;

[0043] Figure 7 The graph shows the changes in electrolytic cell voltage, carbon dioxide release Faraday efficiency, and pH of the cathode and anode chambers during 500 h of continuous operation of the bromine oxidation-reduction mediated electrochemical carbon dioxide capture and release system in Example 5 of this invention.

[0044] Figure 8 a represents 6 × 100 cm in Embodiment 6 of the present invention. 2 Enlarged image of the actual reactor stack. Figure 8 b represents 6×100 cm in Embodiment 6 of the present invention. 2 Scaled-up performance diagram of the reactor stack;

[0045] Figure 9 This is a comparison chart of the theoretical and actual gas production of hydrogen and carbon dioxide in Example 7 of the present invention.

[0046] Figure 10 This is a graph showing the relationship between the mass of ruthenium oxide and the equivalent oxygen current in Example 8 of the present invention. Detailed Implementation

[0047] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0048] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0049] Example 1: As Figure 2As shown, the assembly sequence of the electrochemical reaction module from the cathode side to the anode side is as follows: cathode guide plate 14, cathode limit spacer 15, cathode catalytic electrode 3, anion exchange membrane 5, anode catalytic electrode 4, anode limit spacer 19, anode guide plate 20, and conductive plate 21.

[0050] Specifically, the cathode guide plate 14 is made of pure titanium metal; the anode guide plate 20 is made of graphite to prevent corrosion from bromine in the anolyte, and is equipped with a conductive plate 21, which is made of gold-plated titanium, for connection to the electrochemical workstation and electrochemical testing. The cathode catalytic electrode 3 is a platinum-ruthenium carbon electrode supported on a nickel foam substrate, with an electrochemical reaction area of ​​2 × 2 cm². 2 The anode catalytic electrode 4 is made of hydrophilically treated graphite felt, with an electrochemical reaction area of ​​2 × 2 cm². 2 The anion exchange membrane 5 is AF3-HWK9-75, with an area of ​​3.5 × 3.5 cm². 2 It is sandwiched between the cathode catalytic electrode 3 and the anode catalytic electrode 4. The cathode catalytic electrode 3 and the anode catalytic electrode 4 are respectively provided with openings of 2×2 cm. 2 The cathode limit gasket 15 and the anode limit gasket 19 are used. The electrochemical reaction module is assembled in a detachable manner using fastening bolts.

[0051] The cathode electrolyte is a 1 mol / L potassium bicarbonate solution, with a flow rate of 100 mL / min; the anode electrolyte is a 1 mol / L potassium bromide solution, with a flow rate of 20 mL / min. The cathode guide plate 14 and anode guide plate 20 are respectively provided with flow channels for electrolyte flow. The flow channels of the cathode guide plate 14 are serpentine, ensuring a complete fluid flow path, high electrolyte-plate surface coverage, and no large-area fluid stagnation dead zones, maintaining a relatively uniform distribution of reactants under low current conditions. The anode guide plate 20 is provided with anode plate flow channels. In this embodiment, the anode plate flow channels are interdigitated, composed of multiple sets of interlocking finger-shaped flow channel units. The flow channels are regularly partitioned, resulting in a large effective contact area between the fluid and the anode catalytic electrode 4. Each flow channel branch can disperse the electrolyte and gas relatively uniformly, thereby weakening local concentration polarization. The groove on the anode guide plate 20 and the anode catalytic electrode 4 attached thereto form an anode plate flow channel. The lower port of the anode plate flow channel serves as the anode electrolyte inlet, and the upper port serves as the anode electrolyte outlet. The anode electrolyte passes through the anode catalytic electrode 4 and enters the anode plate flow channel, and flows out from the upper port.

[0052] The reaction principle of this embodiment is as follows: Figure 1 As shown. The hydrogen evolution reaction (HER) occurs at the cathode:

[0053] 2H2O+2e -→H2+2OH - .

[0054] Bromine oxidation (BrOR) occurs at the anode:

[0055] 2Br - +2e - →Br2;

[0056] Br2 + 3H2O - 5e - ⟶BrO3 - +Br - +6H + ;

[0057] Bicarbonate ions in the cathode electrolyte migrate through anion exchange membrane 5 to anode chamber 2 and react with hydrogen ions to produce carbon dioxide.

[0058] H + +HCO3 - →CO2+H2O.

[0059] The electrochemical performance was tested using an Autolab PGSTAT204 electrochemical workstation and a DC power supply.

[0060] Comparative Example 1: The only difference from Example 1 is that the anolyte was replaced with a 1 mol / L potassium bicarbonate solution, and the test was conducted in a three-electrode system. The reference electrode was an Ag / AgCl electrode, which was corrected to a reversible hydrogen electrode using the following formula:

[0061] E(vs. RHE)=E(vs. Ag / AgCl)+0.197 V+0.0591×pH.

[0062] Except for the differences mentioned above, all other conditions and steps are the same as in Example 1. According to Figure 4 The polarization curves show that Example 1 generates a significant positive catalytic current at approximately 1.4 V, indicating a rapid catalytic reaction initiation. In contrast, Comparative Example 1 only shows a significant reaction current at nearly 1.8 V, indicating a significant lag in the reaction initiation potential. At the same current density of 10 mA / cm²... 2 In Example 1, the voltage was reduced by approximately 400 mV compared to Comparative Example 1, indicating that replacing OER with BrOR at the anode can significantly reduce the operating voltage.

[0063] Example 2: The anolyte in Example 1 was replaced with 100 mL of 1 mol / L potassium bromate solution, at 100 mA / cm². 2 Electrolysis was performed at a current density of 60 s, followed by the addition of 50 mg of ruthenium oxide, heating and stirring at 60 °C for 100 s, and then continued at 100 mA / cm². 2 Electrolysis is performed at a specific current density.

[0064] like Figure 5 As shown, in the first 60 seconds of the reaction, the anolyte is mainly potassium bromate, and the OER reaction occurs at the anode, resulting in a high cell pressure. After the addition of ruthenium oxide for catalytic reduction, potassium bromate is reduced to potassium bromide, at which point the anolyte reaction changes to BrOR, and the cell pressure decreases.

[0065] Example 3: Electrochemical performance tests were conducted on Example 1 at different current densities. The test current density was 50 mA / cm². 2 Example 3-1 was obtained, with a test current density of 100 mA / cm². 2 Example 3-2 was obtained, with a test current density of 150 mA / cm². 2 Example 3-3 was obtained, with a test current density of 200 mA / cm². 2 Examples 3-4 were obtained, with a test current density of 250 mA / cm². 2 Examples 3-5 were obtained, with a test current density of 300 mA / cm². 2 Examples 3-6 were obtained, with other conditions and steps being the same as in Example 1.

[0066] Experimental data were obtained by changing the current magnitude, and BrO3 was calculated accordingly. - The results of Faraday efficiency and CO2 release Faraday efficiency are shown in Table 1:

[0067] Table 1

[0068] <![CDATA[BrO3 - Faraday efficiency % <![CDATA[Faradaic efficiency of CO₂ release (%)]]> Example 3-1 99.81 92.27 Example 3-2 99.70 96.35 Example 3-3 99.35 93.92 Examples 3-4 99.75 91.56 Examples 3-5 97.96 90.28 Examples 3-6 97.67 89.38

[0069] BrO3 - Faraday efficiency is calculated according to the following formula:

[0070]

[0071] in, For Br - Oxidized to BrO3 - The number of electrons transferred during the process The number of moles of reactants, expressed in mol. It is Faraday's constant. This represents the total amount of electricity input during the reaction. BrO3 - The concentration was measured using a Thermo Fisher 1100 ion chromatograph.

[0072] The CO2 release Faraday efficiency is calculated using the following formula:

[0073]

[0074] in, The number of electrons participating in the reaction, when bicarbonate ions decompose into CO2. It is usually set to 1. The CO2 flow rate is expressed in mol / s and was measured using a GC7980 gas chromatograph. It is Faraday's constant. This represents electric current, measured in amperes (A).

[0075] The above results indicate that the BrO3 in the six examples - The Faraday efficiency was no less than 97.67%, and the anolyte reaction was successfully replaced by BrOR; the CO2 release Faraday efficiency of each group was higher than 89.38%, especially at 100 mA / cm². 2 At the given current density, the CO2 release Faraday efficiency reached 96.35%, indicating that the carbon capture intermediate can efficiently convert and release CO2.

[0076] Example 4: The only difference from Example 1 is that the interdigitated flow channels on the anode guide plate 20 are replaced with serpentine flow channels and parallel flow channels, respectively. All other conditions and steps are the same as in Example 1. The various schemes using interdigitated flow channels, serpentine flow channels, and parallel flow channels are tested at 100 mA / cm². 2 Electrochemical performance was tested at current density for BrO3. - The Faraday efficiency and CO2 release Faraday efficiency were calculated in the above manner, and the results are shown in Table 2:

[0077] Table 2

[0078] <![CDATA[BrO3 - Faraday efficiency (%) Slot pressure (V) <![CDATA[CO₂ release Faradaic efficiency (%)]]> Interdigitated flow channel 99.7 1.915 96.3 serpentine flow channel 93.5 2.089 89.1 Parallel flow channel 89.3 2.167 81.7

[0079] according to Figure 6 Based on the above test results, under the same electrolysis current density, the interdigitated flow channel requires the lowest full cell voltage and has the highest CO2 release Faraday efficiency, which can reduce the operating energy consumption of the entire electrolysis system. Compared with serpentine and parallel flow channels, the interdigitated flow channel has better mass transfer and CO2 release effects and is more suitable for the anodic BrOR reaction.

[0080] Example 5: Figure 3 As shown, the bromine oxidation-reduction mediated electrochemical carbon dioxide capture and release system includes an electrochemical reaction module, an anolyte circulation module, and a catholyte circulation module. The electrochemical reaction module includes a cathode chamber 1, an anode chamber 2, a cathode catalytic electrode 3 disposed in the cathode chamber 1, an anode catalytic electrode 4 disposed in the anode chamber 2, an anion exchange membrane 5 separating the cathode chamber 1 and the anode chamber 2, and an external DC power supply. This embodiment uses the electrochemical reaction module described in Example 1.

[0081] The anolyte circulation module includes a carbon dioxide release tank 8 and an anolyte regeneration tank 9. The carbon dioxide release tank 8 receives the anolyte flowing from the anode chamber 2 and releases and collects the carbon dioxide under nitrogen purging conditions. The remaining anolyte enters the anolyte regeneration tank 9 via peristaltic pump 13. The anolyte regeneration tank 9 contains a ruthenium oxide catalyst; 50 mg of RuO2 catalyst is added per 100 mL of anolyte. The anolyte regeneration tank 9 is equipped with a stirring and heating device to catalytically regenerate the anolyte treated by the carbon dioxide release tank 8 at 60°C and a stirring rate of 500 rpm, releasing oxygen. The regenerated anolyte returns to the anode chamber 2 via peristaltic pump 12. Both peristaltic pump 12 and peristaltic pump 13 have a flow rate of 20 mL / min.

[0082] The reaction occurring in anolyte regeneration tank 9 is as follows:

[0083] 2BrO3 - →2Br - +3O2.

[0084] The cathode electrolyte circulation module includes a hydrogen separation tank 6 and a carbon dioxide absorption tank 7. The hydrogen separation tank 6 receives the cathode electrolyte flowing from the cathode chamber 1, purges it with nitrogen to release and collect hydrogen, and then pumps the remaining cathode electrolyte into the carbon dioxide absorption tank 7 via peristaltic pump 10. The carbon dioxide absorption tank 7 allows the cathode electrolyte treated in the hydrogen separation tank 6 to absorb carbon dioxide from a mixture of 80% nitrogen, 5% oxygen, and 15% carbon dioxide, thus regenerating the cathode electrolyte. The regenerated cathode electrolyte is then returned to the cathode chamber 1 via peristaltic pump 11. Both peristaltic pump 10 and peristaltic pump 11 have a flow rate of 100 mL / min.

[0085] The reaction occurring in carbon dioxide absorption tank 7 is as follows:

[0086] OH - +CO2→HCO3 - .

[0087] Stability tests were performed on the bromine redox-mediated electrochemical carbon dioxide capture and release system of this embodiment. A constant pressure of 100 mA / cm² was applied during the tests. 2 The current density is monitored using an electrochemical workstation to track changes in the electrolytic cell voltage and to periodically measure the pH at both electrodes. For example... Figure 7 As shown, during the 500-hour long-term electrolysis process, the electrolytic cell voltage only increased by about 195mV, while the CO2 release Faraday efficiency remained at 92%, and the pH at both electrodes did not change significantly. This indicates that the system can maintain good long-term operational stability and has prospects for industrial application.

[0088] Example 6: As Figure 8As shown in Figure a, the electrochemical reaction module uses a 6×100 cm² design. 2 The graphite fuel cell stack, with other conditions and steps being the same as in Example 4. Figure 8 As shown in b, the fuel cell stack is scaled up to a total active area of ​​600 cm². 2 Subsequently, this embodiment tested 50~450mA / cm 2 It can maintain a high CO2 release Faraday efficiency over a wide current density range, especially at 200 mA / cm². 2 Under normal operating conditions, the CO2 release Faraday efficiency reaches its peak, and no significant decrease in efficiency occurs under low and medium load conditions, making it suitable for continuous production under varying loads in factories.

[0089] Furthermore, at 450 mA / cm 2 At current density, the 6×100 cm 2 The fuel cell stack is capable of operating at kilowatt-level power, with a CO2 release Faraday efficiency of 76.83%.

[0090] The CO2 release Faraday efficiency was calculated as described in Example 3, and the power was calculated according to P=U×I, where U is the cell voltage and I is the total current.

[0091] Example 7: at 100 mA / cm 2 Under current density conditions, the H2 generated at the cathode and the CO2 released at the anode were collected separately using the water displacement method, and the actual gas production was compared with the theoretical gas production. The theoretical gas production volume was calculated using the following formula:

[0092]

[0093] in, The number of electrons participating in the reaction. It is Faraday's constant. Current, in amperes (A). Time, in seconds. For the temperature, this embodiment uses room temperature (300 K). Let be the ideal gas constant. Standard atmospheric pressure.

[0094] like Figure 9 As shown, within the electrolysis time range of 1 to 5 min, the actual hydrogen evolution volume of the system is basically consistent with the theoretical hydrogen evolution volume; the actual CO2 release volume increases linearly and steadily with the reaction time, and the actual CO2 release at each time point is highly matched with the theoretical release, indicating that the system can simultaneously achieve stable and efficient H2 generation and CO2 release.

[0095] Example 8: 100 mL of 1 mol / L potassium bromate solution was used, and 10 mg, 20 mg, 30 mg, 40 mg, and 50 mg of ruthenium oxide were added respectively. Oxygen was collected by water displacement under a stirring rate of 500 rpm, and the equivalent oxygen current was calculated. The equivalent oxygen current was calculated according to the following formula:

[0096]

[0097] in, The oxygen-related current density is normalized to the mass of ruthenium oxide, expressed in mA / mg RuO2, and is used to characterize the activity of catalyst per unit mass. The number of electrons participating in the reaction is 4 for O2; It is Faraday's constant; The oxygen generation rate is measured by the water displacement method, in L / s; 22.4 is the gas volume constant under standard conditions. The value represents the mass of ruthenium oxide, expressed in mg.

[0098] like Figure 10 As shown, when the ruthenium oxide feed amount is less than 40 mg, the mass transfer and interfacial reaction conditions of the catalytic system improve with increasing catalyst dosage, and each milligram of RuO2 can exhibit higher activity. When the ruthenium oxide feed amount exceeds 40 mg, excessive catalyst will cause particle stacking and cover the active sites, resulting in limited mass transfer between the electrolyte and reactants, decreased catalyst utilization efficiency per unit mass, and consequently reduced mass activity. Under the condition of 100 mL anolyte, a ruthenium oxide feed amount of 40 mg has the highest utilization rate.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A bromine redox-mediated electrochemical carbon dioxide capture and release system, characterized in that, It includes an electrochemical reaction module, an anolyte circulation module, and a catholyte circulation module; The electrochemical reaction module includes a cathode chamber, an anode chamber, a cathode catalytic electrode and an anode catalytic electrode respectively disposed in the cathode chamber and the anode chamber, and an anion exchange membrane separating the cathode chamber and the anode chamber; in the cathode chamber, the cathode electrolyte undergoes a hydrogen evolution reaction to generate hydrogen gas and hydroxide ions; in the anode chamber, bromide ions in the anode electrolyte undergo a bromine oxidation reaction to form bromate ions and hydrogen ions; and bicarbonate ions in the cathode electrolyte migrate to the anode chamber through the anion exchange membrane and react with hydrogen ions to generate carbon dioxide. The anolyte circulation module includes a carbon dioxide release tank and an anolyte regeneration tank. The carbon dioxide release tank is used to receive the anolyte flowing out of the anode chamber and separate the carbon dioxide therein. The anolyte regeneration tank is used to thermally catalyze the anolyte treated by the carbon dioxide release tank, so that bromate ions are converted into bromide ions and oxygen is generated. The regenerated anolyte is returned to the anode chamber. The cathode electrolyte circulation module includes a hydrogen separation tank and a carbon dioxide absorption tank. The hydrogen separation tank is used to receive the cathode electrolyte flowing out of the cathode chamber and separate the hydrogen therein. The carbon dioxide absorption tank is used to allow the cathode electrolyte treated by the hydrogen separation tank to absorb carbon dioxide from the mixed gas containing carbon dioxide. The regenerated cathode electrolyte is returned to the cathode chamber.

2. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 1, characterized in that, The electrochemical reaction module is provided with a cathode guide plate, a cathode limit gasket, a cathode catalytic electrode, an anion exchange membrane, an anode catalytic electrode, an anode limit gasket, and an anode guide plate in sequence from the cathode side to the anode side. A conductive plate is provided on the outer side of the anode guide plate.

3. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 1, characterized in that, The anode catalytic electrode is a hydrophilically treated graphite felt.

4. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 1, characterized in that, The cathode catalytic electrode is a platinum-ruthenium carbon electrode supported on a nickel foam substrate.

5. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 1, characterized in that, The anion exchange membrane is a polyimide anion exchange membrane.

6. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 1, characterized in that, The anolyte is a potassium bromide electrolyte solution, and the cathode electrolyte is a potassium bicarbonate electrolyte solution.

7. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 2, characterized in that, The anode guide plate is provided with an anode plate flow channel, which is one of an interdigitated flow channel, a serpentine flow channel, or a parallel flow channel.

8. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 7, characterized in that, The anode plate flow channel is an interdigitated flow channel.

9. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 1, characterized in that, The anolyte regeneration tank is equipped with a ruthenium oxide catalyst and a stirring and heating device.

10. The bromine redox-mediated electrochemical carbon dioxide capture and release system according to claim 1, characterized in that, Both the cathode liquid circulation module and the anolyte circulation module are equipped with a conveying device for driving the electrolyte circulation flow.

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